Human Chorionic Gonadotropin (hCG, choriogonadotropin), a hormone normally secreted by the placenta during pregnancy, has been shown to be present in the blood of patients with a wide variety of cancers, but not detectable in the blood of non-pregnant controls. The purpose of the present proposal is to isolate and characterize chorionic gonadotropin from human placenta, from the urine of cancer patients, testicular and ovarian tissue extracts, from the tissue culture fluid of ovarian adenocarcinoma cells which are producing hCG in vitro. The chemical characterization would involve molecular weight determination, aminoacid composition, carbohydrate composition, amino and carboxy terminal analysis, dissociation into subunits and aminoacid and carbohydrate sequencing. A highly specific, high-titer antisera will be developed against the carboxy terminal 28 residue peptide of the hCG beta subunit, to be used as an immunodiagnostic reagent in cancer detection.